Control apparatus



March 16, 1948 M. E. CHANDLER CONTROL APPARATUS Original Filed Jan. 25, 1944 I INVENTOR MTUNE Lhwzm AGENT Related Mar. 16, 1948 CONTROL APPARATUS Milton E. Chandler, New Britain, Coma, assignor, by mesne assignments, to Nilec-BemenhPond Company, West Hart! oi New Jersey ord, Conm, a cumntion Original No, 2,394,664, dated February 12, 19133,

Serial No, 519,611, January 25, 1944. Application for reissue October 1, 1948, Serial No.

14 Claims.

1 The present invention relates to control appa ratus for internal combustion engines, and particularly to a safety control apparatus for the throttle of such an engine. In internal combustion engines, such as those used on aircraft, it is sometimes desired to limit the maximum power output of the engine in order to prevent the operator from running the engine under overload conditions; In engines such as aircraft engines, where the throttle is located at some distance from the pilots control lever and is connected 'to that lever by a rather complicated linkage, it is also desired to provide some means to limit the minimum power output of the engine upon failure of the control linkage.

It is therefore an object of the present inven-.

tion to provide improved means for limiting the movement of the throttle of an internal combustion engine.

Another object is to provide means for limiting the opening movement of the throttle of an internal combustion engine so as to provide a substantially constant maximum air flow to the engme.

Another object is to provide improved means for controlling the throttle of an intemai combustion engine so as to secure a substantially constant flow of air to the engine.

Another object is to provide-improved means responsive to the position of the, throttle for controlling the fuel flow under idling conditions.

A further object is to provide improved means for preventing closure of the throttle beyond a 2 engine, In certain cases the supercharger may be upstream from the inlet l2, or two superchargers may be used, one in each place.

The Venturi restriction it produces a pressure differential between the inlet 32 andthe threat 0! the restriction which varies in accordance with the square of the velocity of the air passing thru the restriction. Since the cross-section of the venturi is constant, this pressure differential may be taken as a measure of the volume of air flowing thru the passage.

In order to control combustion conditions within the engine, it is necessary to control the fuel flow in proportion to the air flow. The iuel'ilow is controlled in accordance with the mass of air flowing, rather than its volume, because the darn sity of the air varies in accordance with its pressure and temperature, which are in turn affected by external atmospheric conditions and by the altitude at which the aircraft is flying.

As previously stated, the pressure diflerential between the entrance I2 and the throat of Venturi l4 varies as a function of the volume of air flowing thru the venturi. In order to obtain a presas sure diflerential varying as a function of the mass partially open position in the event that the manual control linkage fails.

A still further object is to provide an arrangement of the type described in which the idlin control mechanism serves to operate the throttle to a partially open position upon failure of the manual control linkage.

Other objects and advantages of the present invention will become apparent from a consideration of the appended specification, claims and drawing, in which the single figure represents a carburetor for an internal combustion engine provided with control apparatus embodying the principles of my invention.

Referring to the drawing, there is shown a body ID of a carburetor for an internal combustion engine of a type used on aircraft. Air enters the carburetor body ID at an inlet l2 and flows thru a Venturi restriction l4 and a passage I5, past a throttle l6 and a fuel discharge nozzle ii to an outlet 20. A supercharger may be provided beof air flowing thru the venturi I4, the pressure difl'erential between entrance I! and the throat oi venturi I4 is utilized to create an air flow thru a secondary air-passage extending from entrance H to the throat of venturi ll, A plurality of impact tubes 22 are provided, whose open ends proiect into the entrance i2 to receive the impact of the entering air. The secondary air passage may be traced from entrance l2, thru tubes 22, a passage or vent ring 24 interconnecting the impact tubes, a conduit 26, a chamber 28 ina pressure meter generally indicated at 30, a restriction 32, a chamber 34 inthe pressure meter 30, a conduit 3|, past a valve 38 into a chamber 40, and thence thru a conduit 42 to the throat of Venturi It.

The valve 38 is controlled by a sealed bellows {I mounted in the chamber 40. The bellows 4 4 is fixed at one end, so that the position of the free end, to which valve 38 is attached, varies in accordance with the air pressure in the chamber 40. The bellows 44 is preferably filled with nitrogen or some other suitable temperature responsive fluid, so that the position of valve- 3! varies not only with the pressure but with the temperature of the air in the chamber Ill, and hence with the density of that air.

In the secondary air passage, the pressure dilferential betweenthe entrance l2 and the throat of venturi .II is divided into two component prestween the outlet 20 and the intake manifold or the 86 sure drops. one across the restriction 32 and the across valve 88 to increase, and the pressure drop across restriction 82 to decrease. By proper design of valve 88, the pressure drop across restriction 82 may be made to vary substantially in accordance with the mass of air flowing thru passage I8. This pressure diflerentialacross restriction 82 acts on a diaphragm 48 which separates the chambers 28 and 84. The force applied to diaphragm 48 is transmitted to a valve 48, on which it acts in a vclosing direction.

The fuel enters the carburetor from a fuel pump or other source of fuel under superatmospheric pressure thru a conduit 88 and flows thru a, valve 82 in a pressure regulator generally indicated at 84, a conduit 88, an idle control I28, a conduit 81, a mixture control generally indicated at 88, a Jet system 88, a conduit 82, a valve 84 in a second pressure regulator 88, and a conduit 88 to the fuel discharge nozzle I8.

The pressure regulator 84 includes a diaphragm l8 separating a pair of expansible chambers 12 and 14 and connected at its center to the valve 82. A spring 18 biases the valve 82 towardopen position. A restriction I8 connects the chambers 12 and 74.

A portion of the fuel entering pressure regu later 84 flows thru chamber 14, restriction I8, chamber 12,, a conduit 88, a chamber 82 in the pressure meter 38, past the valve 48, and thru a conduit 84 to a suitable drain, which may, for example, empty into the main air passage ii. If desired, the drain may be connected to the main fuel tank, or the fuel flowing thru it may be otherwise disposed of.

The pressure meter 88 includes a diaphragm 88 separating the chambers 84 and 82 and a diaphragm 88 separating the chamber 28 from a fourth expansible chamber 88. The valve 48 is biased toward closed position by a spring 82.

The chamber 88 is connected thru a conduit 94 to the fuel conduit 82 downstream from the 4 carburetor, and the other in accordance with, the mass of fuel entering the carburetor. Furthermore, the valve 48 controls the mass of fuel entering the carburetor, since it controls the pressure in chamber 82. The Pressure in the chamber 82 is transmitted to chamber 12 of pressure regulator 84 where it controls the position of valve 82 and hence the pressure on the upstream side of the Jet system 88. The pressure on theupstream side of let system 88 is therefore varied as a function of the mass of air flowing to the engine for combustion purposes.

The pressure regulato 88 operates to maintain a substantially constant pressure on the downstream side of the jet system 88 and thereby to prevent variations in pressure at the fuel discharge nozzle I8, which may be due to operation of the throttle or to variations in engine speed, from reaching the downstream side of the jet system and affecting the fuel flow.

Since the pressure on the downstream side of the Jet system 88 is held constant and the pressure on the upstream side is varied as a function of the air flow, it may be seen that for a given constant cross-sectional area of the Jet system, the fuel flow is proportioned to 'the air flow. The mixture control 88 may be operated to vary the crosssectional area of the Jet system and hence to vary the fuel to air ratio.

The pressure regulator 88 includes a pair of expansible chambers 88 and 88 separated by-a flexible diaphragm I88, which is attached at its center to the valve 84. A spring I82 biases the valve 84 toward closed position. The chamber 98 is connected thru a conduit I84 to the conduit 28 and thence thru the vent ring 24 and impact tubes 22 to the air entrance I2. The chamber 88 is connected to the fuel conduit 82.

The mixture control 88 includes a disc valve I88 fixed on a shaft I88. The disc valve I88 controls the flow of fuel thru ports opening into conduits H8 and H2 which lead into the jet system 88. When the disc I88 is in the position illustrated in full lines in the drawing, fuel can flow to the Jet system only thru the conduit II8. This full line position of the disc valve I88 is known as the lean" position of the mixture control 88., When the disc valve I88 is in the dotted line position shown in the drawing, the fuel can flow thru both the conduits H8 and H2. The

- dotted line position of disc valve I88 is termed jet system 88. The pressure in chamber 88 is therefore the same as that in the fuel line downstream from the Jet system. The pressure in chamber 82 is the same as that in chamber 12 of pressure regulator 54. The pressure in chamber I2 differs from the pressure in chamber I4 by a fixed amount which depends on the strength of spring I8. Therefore the pressure in chamber 12 is a measure of the pressure on the upstream side of the Jet system 88. For any given constant cross-sectional area of the fuel passage thru the jet system 88', the pressure differential across it is a measure of the fuel flow thru it. This pressure differential. or rather a. smaller pressure differential which is a measure of the pressure diflerential across the jet system, is applied thru the diaphragms 88 and 88 of pressure meter 88 to the valve ,48, on which it acts in an opening direction.

From the foregoing, it may be seen that thevalve 48 is positioned in accordance with the balance between two forces, one of which varies in accordance with the mass of air entering the the rich" position of the mixture control.

he conduit 8 conducts fuel either thru a fixed restriction or Jet H4, or thru a restriction II8 controlled by a valve II8 biased to closed position by a spring I28. The conduit II2 conducts fuel to aflxed restriction I22. Fuel flowing thru the restrictions H8 and I22 also flows thru another restriction I24 which determines the maximum flow thru restrictions H8 and I22.

The valve II8 opens only at high pressure difierentials across the jet system to increase the fuel to air ratio under heavy load conditions.

The idle control I28 includes a valve I28 attached to the center of a diaphragm I38. A spring I32 biases the valve I28 in an opening direction. A stop I84 is provided to limit the opening movement of valve I28. An elongated stem I38 extends outwardly from the side of diaphragm I38 opposite the valve I28.

The throttle I8 is fixed on a shaft I38. An arm I48 is also fixed on shaft I88. The end of arm I48 is pivotally connected to a link I42 whose opposite end is pivotally attached to an arm I44 which rotates on a pivot I48. The opposite end A lever Illlis mounted to freely rotate on the throttle shaft Ill. One end of the lever I50 is pivotally attached to a link I52 which may extend thru a linkage train (not shown)v to the throttle control lever in the pilot's compartment. The opposite end of lever I40 carries a stop I54 which extends into the path of movement of arm I40. A spring I40 biases the arm I40 into engagement with the stop I04.

The opening movement oi the throttle is limited by a stop mechanism generally indicated at I58. The stop mechanism I58 includes a bellows I60 whose interior is connected. thru a conduit I52 to the fuel conduit 55. d compression spring I84 biasesthe free end of-b'ellows I40 for movement to the left. A stop member IE6 is attached to the free end of bellows I40, and the opposite .end of stop member I50 extends into the path of movement of the upper end of arm I44.

In order to move the throttle toward open position, the pilot moves his control lever o as to move link I52 to the right. This causes a counterclockwise movement of lever I50. Since the arm I40 is held in engagement with stop I54 by spring I56, it follows thecountercloekwise movementof lever I50. Since the arm I40 is flxed on the shaft I38, the latter is. also rotated, thereby moving the throttle IS in an opening direction.

This opening movement can continue under the control of the manually operated link I52 until the upp r end of arm I44 engages the stop member I66. Thereafter, if the link I52 is moved further to the right, the arm I40 does not follow the lever I50,but the spring I! is stretched and the stop I54 separates from the arm 140.

The position of the throttle atsuch atime is determined by the position of stop I88. The position of stop I66 in turn depends upon the pressure in conduit 55 and hence on the regulated pressure in chamber 14 oi pressure regulator 54. As previously described, the pressure in chamber 14 varies as a function of the mass of airflowing to the engine thru the venturi I4.

Under these conditions, the throttle I5 is con trolled to maintain a substantially constant air flow. If the air flowing to the engine should increase, there would be a resulting increase in the pressure in chamber 14. This increased pressure in hamber I4 is transmitted to bellows I50 where it acts thru the stop I55 to move the throttle ill in a closing direction, thereby decreasing the air flow. Therefore the systemtends to maintain a constant air flow. The value of this air flow may beadjusted by changing the tension of spring I64 and hence the position at whichstop I 66 is maintained for a given value of air flow. Although no means is illustrated for changing the tension of spring I54, such means are common and may readily be provided.

At low,ai flows, such as are encountered under I idling conditions, the pressure differential set up by the venturi I4 tends to be erratic, and is not a reliable indication of the volume of air entering the engine. Provision is made to transfer control of the fuel flow to the throttle at such times. The spring 02 in the pressure meter 36 acts on valve 48 in a closing direction. When the difl'erentiai pressure acting on diaphragm 45 istsmall, as under low air flow conditions, the spring 92 is the predominating force acting on valve 48. A

closing movement-of valve 44 causes an increase in the fluel flow thru the main the! line, since the closure of valve 44 increases the pressure in chamber 82 or pressure meter 40 and hence in chamber 12 of pressure regulator 54. This causes an opening movement of valve 52 until a balancing increase is produced in the pressure in chamber I4, which is the same as the pressure on the upstream side of the jet system 50. Furthermore, the spring Idol pressure regulator 54 biases valve 52 in an opening or fuel flowincreasing direction.

As the throttle I8 approaches its idling position, the link I44 is rotated clockwise and its lower end I48 engages the end of valve stem I36 and operates the idle control I26 so as to move valve I28 in a closing direction. Under such conditions, the quantity of fuel supplied to the engine is determined by the throttle position as that position is reflected in the position of valve I28. This is in contrast to the operation-oi the system at higher air flows when the fuel supply is determined by the mass of air entering the engine as measured by pressure meter 30.

,If the linkage connecting the link I52 with the pilot's control lever should fail, then the maximum opening position of the throttle would be limited by the stop mechanism I58 and the maximum closing position would be limited by valve stemi35. Therefore the engine would continue to operate and drive the aircraft, even though its speed of operation could not be predicted. This might be of considerableadvantage to the occupants of the aircraft. For example, under combat conditions, it might enable the aircraft to return to its base even though the throttle control was not operative. The throttle could not move to its fully closed positionand cut oil the engine, nor could it move to its fully open position and cause the engine to become overheated.

While I have shown and described a preferred embodiment of my invention, it will be readily understood by those skilled in the art that other modifications may be made without departing from the scope of the invention as defined in the appended claims.

I claim as my invention: p

1. Control apparatus for an internal combustion engine comprising throttle means for controlling the flow of air to said engine, manually movable means for positioning said throttle 'means, stop means for limiting the opening movement of said throttle means, spring means permitting additional movement of said member after said throttle means engages said stop means. a conduit for fuelflowingto said engine, means responsive to the quantity of air flowing to said engine for controlling a fuel pressure in said conduit, means responsive to said controlled pressure for positioning said stop means, valve means in said fuel conduit, means biasing said valve means toward open position, abutment means asminai value to control a pressure in said fuel' sociated with said valve'means and said throttle means and adapted to engage when said throttle means is adjacent its closed position to cause a following movement of said valve means, said biasing means being efl'ective upon failure of said manually movablemeans to movesaid throttle means to a partially open position.

2. Control apparatusfor an internal combustion engine, comprising a first conduit for air flowing to said engine for combustion purposes, throttle means for controlling the flow of air thru said conduit, a second conduit for fuel flowing to said engine, means responsive to the quantity of air flowing thru said first conduit and effective when said quantity exceeds a predeterconduit, means effective when said quantity is oases 7 less than said value to increase said pressure disproportionately to said quantity, valve means in said second conduit for controlling the fuel flow therethru, spring means biasing said valve means toward open position, means responsive to said pressure and acting on said valve means in an opening direction, and a member connected to said throttle means for movement therewith, said member being positioned adjacent said valve means and adapted to engage said valve means to cause a following movement thereof whenever said throttle means is in a position corresponding to a quantity of air less than said predetermined value.

3. Control apparatus for an internal combustion engine, comprising a flrst conduit for air flowing to said engine for combustion purposes, throttle means for controlling the flow of air thru said conduit, manually movable means for positioning said throttle means, a second conduit for fuel flowing to said engine. means responsive to the quantity of air flowing thru said first conduit and efiective when said quantity exceeds a predetermined value to control .the flow thru said fuel conduit, valve means in said second conduit for additionally controlling the fuel flow therethru, spring means biasing said valve means towards open position, means responsive to the pressure in said fuel conduit and acting on said valve means in an opening direction, and a member connected to said throttle means for movement therewith, said member being positioned adjacent said valve means and adapted to .engage said valve means to cause a following movement thereof whenever said throttle means is in a position corresponding to a quantity of air less than said predetermined value, said spring means and said fuel conduit pressure being effective upon failure of said manually movable means to move said throttle means to a partially open position.

4. Control apparatus for an internal combustion engine, comprising throttle means for con trolling the flow of air thru said conduit, manually movable means for positioning said throttle means, a second conduit for fuel flowing to said engine, valve means in said second conduit for controlling the fuel flow therethru, spring means biasing said valve means toward open position, and a member connected to said throttle means for movement therewith, said member being positioned adjacent said valve means and adapted to engage said valve means to cause a followin movement thereof whenever said throttle means is in a position adjacent its closed position, said spring means being effective upon failure of said manually movable means to'move said throtti means to a partially open position.

5. Control apparatus for an internal combustion engine is an aircraft, comprising throttle means for controlling the flow of air to said engine for combustion purposes, a manually movable control member remote from said throttle means, linkage connecting said member and said throttle means, a conduit for fuel flowing to said engine, valve means in said conduit for controlling the fuel flow therethru, spring means biasing said valve means toward open position, and a member connected to said throttle means for movement therewith, said member being positioned adjacent said valve means and adapted to engage said valve means to cause a following movement thereof whenever said throttle means is in a position adjacent its closed position, said spring means being'eilective upon failure of said 8 linkagetomove saidthrottlemeanstoapartially open position.

6. Control apparatus for an internal combustion engine, comprising a throttle for controlling the flow of combustion air to said engine, means for positioning said throttle, a member connected to said throttle for concurrent movement therewith, an abutment for engaging said member to limit the free movement of said throttle toward closed position, resilient supporting means for said abutment so that said throttle may be moved beyond the limiting position established thereby, said abutment and said resilient supporting means being effective on failure of said throttle positioning means to move said throttle to a partially open position, a fuel conduit, and a valve in said conduit adapted to control the total flow of fuel to said engine: said resilient supporting means being eflective upon continued movement of said positioning means in a throttle closing direction after engagement of said abutment by said member to operate said valve toward closed position.

7. Control apparatus for an internal combustion engine in an aircraft, comprising throttle means for controlling the flow of air to said engine for combustion purposes, a manually movable control member remote from said throttle means, linkage connecting saidmember and said throttle means, a conduit for fuel flowing to said engine, valve means in said conduit for controlling the total fuel flow to said engine, means biasing said valve means toward open position, and a member connected to said throttle means for movement therewith, said member being positioned adjacent said valve means and adapted to engage said valve means to cause a following movement thereof whenever said throttle means is in a position adjacent its closed position, said biasing means being effective upon failure of said linkage to move said throttle means to a partially open position.

8. Control apparatus for an internal combustion engine in an aircraft, comprising throttle means for controlling the flow of air to said engine for combustion purposes, a manually movable control member remote from said throttle means, linkage connecting said member and said throttle means, a conduit for fuel flowing to said engine, valve means in said conduit for controlling the fuel flow therethru, means for applying an opening force to said valve means including a diaphragm subject to fuel pressure in said fuel conduit, and a member connected to said throttle means for movement therewith, said member being positioned adjacent said valve means and adapted to engage said valve means to cause a following movement thereof whenever said throttle means is in a position adjacent its closed position, said force applying means being effective upon failure of said'linkage to move said throttle means to a partially open position.

9. Control apparatus for an internal combustion engine in an aircraft, comprising throttle means for controlling the flow of air to said engine for combustion purposes, a manually movable control member, means operatively connecting said member and said throttle means, a conduit for fuel flowing to said engine, valve means in said conduit for controlling the total fuel flow to said engine, spring means biasing said valve means toward open position, and an abutment means and adapted to engage said valve means to cause a closing movement thereof whenever said manual control member is in a position ads-s controlling the flow of air thru said conduit means for positioning said throttle, a second conduit for fuel flowing to said engine, means for regulating the pressure in a portion of said fuel conduit to control the fuel flow therethru, a valve in said fuel conduit for additionally controlling the fuel flow therethru, means responsive to the fuel pressure in 'said conduit portion and acting on said valve in an opening direction, a member connected to said throttle for movement therewith, an abutment connected to said valve and positioned in the path of, said member so that when said throttle approaches closed position, said member engages said abutment and moves said valve toward closed position against the action of said fuel pressure responsive means.

11. Control apparatus as in claim 10, in which said fuel pressure responsive means is effective upon failure of said throttle positioning means to move said throttle to a partially open position,

12. Control apparatus as in claim 11 in which said fuel pressure regulating means is responsive to the rate of flow of air thru said first conduit.

13. Control apparatus for an internal combustion engine, comprising a first conduit for combustion air flowing to said engine, a throttle for controlling the flow of air thru said conduit. means for positioning said throttle, a second conduit for fuel flowing to said engine, means for regulating the pressure in a portion of said fuel conduit to control the fuel flow therethru, member connected to said throttle for movement therewith, an abutment positioned in the path of said member for limiting the free movement of said throttle in a closing direction, said abutment being movable between a first position corthrottle and a second position corresponding to the closed position of said throttle, and means including a diaphragm subject to the fuel pressure in said conduit portion for moving said abutment to said first position in response to said pressure, said abutment moving means being effective upon failure of said throttle positioning means to move said throttle to a partially open position.

14. Control apparatus for an internal combustion engine, comprising a throttle for controlling the flow of combustion air to said engine,

' ure of said throttle positioning means to move responding to a partly open position of said said throttle to a partially open position, a fuel conduit, a valve in said conduit for controlling the total fuel flow to said engine, and a stem for said valve movable concurrently with said abutment, and eflective upon continued movement of said member in a throttle closing direction after engagement with said abutment to move said valve toward closed position.

' MILT ON E. CHANDLER.-

REFERENCES crrnn The following references are of record in the file of this patent:

" UNI'I'ED STATES PATENT Number 0 Name Date 2,002,483 Kimball May 21, 1935 2,009,109 Hunt July 23, 1935 2,155,560 Malouf -1 Apr. 25,- 1939 2,189,705 Chandler Feb. 6, 1940 2,205,458 Ball June 25, 1940 2,361,227. Mock Oct. 24, 1944 FOREIGN PATENTS Number Country Date Great Britain Aug. 19, 1936 

